PROBLEM TO BE SOLVED: To provide an underpants type disposable diaper that has excellent easiness of stretching when a waist part is expanded with hands brought into contact with the inside of the waist part.SOLUTION: The problem is solved by such a structure that: a stretchable region extending at least from a side edge of an interior body 200 to a side seal part 12A in a waist part of an exterior body 12 includes a first sheet material 12S, a second sheet material 12H opposed to one surface of the first sheet material 12S, and plural elongated elastically stretchable members disposed with a spacing between adjoining ones in a width direction between the first sheet material 12S and second sheet material 12H the first sheet material 12S and second sheet material 12H are joined through adhesion processing, which is performed continuously in a lengthwise direction and applied intermittently in a width direction, in order to form a sheet joint part 70 the elastically stretchable member is fixed to at least one of the first sheet material 12S and second sheet material 12H with an adhesive 71 at at least both ends thereof at least a portion of the stretchable region in the lengthwise direction includes on the side of the side seal part 12A a short stretchable region 90 whose stretchable length is shorter than that of the interior body 200 and whose width is larger than that of the sheet joint part 70.
